1. Field of the Invention
The present invention relates to a sheet member feeding apparatus which can smoothly feed a sheet member including an envelope and the like, without jamming.
2. Related Background Art
A regist feeding portion in a conventional sheet member feeding apparatus for feeding a sheet member or material including an envelope and the like comprises, as shown in FIG. 1, a metallic roller 1 and a rubber roller 2 which are engaged by each other to rotate and stop altogether.
Explaining an operation of such conventional mechanism, in a condition that the metallic roller 1 and the rubber roller 2 are maintained stationary, a leading edge 31 of an envelope 3 fed through a guide member (not shown) such as a guide plate is first abutted against an outer peripheral surface of the metallic roller 1 and then is gradually sent toward a nip portion 5 between the metallic roller 1 and the rubber roller 2 along the outer peripheral surface of the metallic roller 1. Further, since the envelope 3 is fed by a predetermined distance by means of a sending means (not shown) acting on a trailing edge 32 of the envelope, a predetermined amount of loop is formed in the envelope 3. Even if the envelope is skew-fed with either one of left and right corners of the leading edge 31 being ahead of the other, the difference in amount created in the skew feeding is absorbed during the loop formation, and, consequently, the left and right corners of the leading edge 31 of the envelope are abutted against the nip portion 5 between the rollers 1, 2, thus compensating for the skew feeding of the envelope. Thereafter, the envelope 3 is correctly fed to a desired position through the rotation of the metallic roller 1 and the rubber roller 2.
In some cases, as shown in FIG. 2, the envelope 3 has a protruding folded portion at a corner 41 thereof. In this case, when the envelope is skew-fed with the protruding corner 41 being ahead of the other corner, as shown in FIG. 3, the corner 41 having the protruding folded portion will first be engaged by the nip portion 5. However, if the protruding folded portion of the corner 41 is curled at a point 42, the protruding corner 41 is engaged only by the rubber roller 2, and, thus the curl 42 grows more and more (in a direction shown by an arrow A). Consequently, the corner 41 cannot reach the nip portion 5 between the metallic roller 1 and the rubber roller 2, with the result that the envelope is not fed even when the rollers 1 and, 2 are rotated, thus causing so-called "pre-regist jam".